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Anomalous residual austenite formation in root of welding layers of 9% Cr/CrMoV dissimilar welded joint

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Journal of Iron and Steel Research International 2018年第8期25卷 839-846页

作者： Kai Ding Hui-jun Ji Quan-liang Zhang Xia Liu Peng Wang Xiao-hong Li Ling Zhang Yu-lai Gao State Key Laboratory of Advanced special Steel State Shanghai Key Laboratory of Advanced FerrometallurgySchool of Materials Science and Engineering Shanghai University Shanghai 200444 China Shanghai Turbine Plant Shanghai Electric Power Generation Equipment Co. Ltd. Shanghai 200240 China

The morphology and distribution of residual austenite in the welded zone of 9% Cr/CrMoV dissimilar welded joint were observed by color metallographic method. Moreover, the details of the distribution, shape, length, length-to-width ratio, and the content of residual austenite in each welding layer were systematically characterized using Image-Pro Plus image analysis software. Different from the techniques such as X-ray diffraction, vibrating sample magnetometer, and electron backscatter diffraction that only involve the content of residual austenite, color metallographic method can offer much more details of the residual austenite, including the location, shape, size, and content, helping evaluate the overall characteristics of the residual austenite produced in the weld. It is interesting that a large amount of block-like and film-like residual austenite was found in the root of each welding layer, while rare at the top. The area fraction of residual austenite located in this zone was approximately 7.5% compared with only 0.5% at the top. In addition, the average area, length, and length-to-width ratio of dispersed residual austenite were quantitatively evaluated to be （4.7 ± 0.6）μm2, （5.1 ±0.6） μm, and （1.1 ± 0.1） μm, respectively. This variety of residual austenite was resulted from the tempering effect by latter welding layer on the previous one and different cooling rates in these two regions during the welding process.

关键词： Residual austenite Color metallographic method Dissimilar welded joint Narrow gap submerged arcwelding Multilayer and multi-pass welding

Phthalocyanine-derived catalysts decorated by metallic nanoclusters for enhanced CO_(2)electroreduction

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Green Energy & Environment 2023年第2期8卷 444-451页

作者： Jiacheng Chen Jiayu Li Jing Xu Minghui Zhu Yi-Fan Han State Key Laboratory of Chemical Engineering School of Chemical EngineeringEast China University of Science and TechnologyShanghai200237China

Electrochemical CO_(2)reduction(CO_(2)RR)over molecular catalysts is a paramount approach for CO_(2)conversion to ***,we report a novel phthalocyanine-derived catalyst synthesized by a two-step method with a much improved ***,the catalyst contains both Ni-N4sites and highly dispersed metallic Ni nanoclusters,leading to an increased CO_(2)RR currents by two *** labelling study and in situ spectroscopic analysis demonstrate that the existence of metallic Ni nanoclusters is the key factor for the activity enhancement and can shift the CO_(2)RR mechanism from being electron transfer(ET)-limited(forming*COO^(-))to concerted proton-electron transfer(CPET)-limited(forming CO).

关键词： Carbon dioxide Electroreduction Hybrid catalyst Nickel-based catalysts Mechanism

The capillary pressure curves from upscaling interfacial and unsaturated flows in porous layers with vertical heterogeneity

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Theoretical & Applied Mechanics Letters 2023年第4期13卷 287-290页

作者： Zhong Zheng State Key Laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China MOE Key Laboratory of Hydrodynamics School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

We provide the capillary pressure curves p_(c)(s)as a function of the effective saturation s based on the theoretical framework of upscaling unsaturated flows in vertically heterogeneous porous layers proposed recently(***,Journal of Fluid Mechanics,950,A17,2022).Based on the assumption of vertical gravitational-capillary equilibrium,the saturation distribution and profile shape of the invading fluid can be obtained by solving a nonlinear integral-differential *** capillary pressure curves p_(c)(s)can then be constructed by systematically varying the injection *** with the relative permeability curves k_(rn)(s)that are already *** can now provide quick estimates on the overall behaviours of interfacial and unsaturated flows in vertically-heterogeneous porous layers.

关键词： Flow upscaling Interfacial and unsaturated flow Wetting and capillary effects Porous layer Heterogeneity

Thickening of Non-Ferroelectric Capacitive Layers with Enhanced Domain Switching Speed in Polyvinylidence Fluoride Copolymer Thin Films

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Chinese Physics Letters 2011年第10期28卷 236-239页

作者： LIU Xiao-Bing MENG Jian-Wei JIANG An-Quan WANG Jian-Lu State Key Laboratory of ASIC and System Department of MicroelectronicsFudan UniversityShanghai 200433 National Laboratory Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083

The large coercive field of domain switching in poly(vinylidene fluoride-trifluoroethylene)thin films is in much part due to the contribution of nonpolar impurity phases rather than the manifestation of an intrinsic domain switching mechanism of the ferroelectric *** coincidentally derive the equivalent electrical capacitance for the total non-ferroelectric capacitive layers from either domain switching current transient or voltage dependence of the switched ***,the non-ferroelectric capacitance reduces by more than 71%with the enhancement of domain switching speed spanning over 5 orders of magnitude in company with the continuous reduction of the remanent polarization,which suggests the thickening of the above capacitive layers with enhanced domain switching speed.

关键词： ferroelectric capacitance Copolymer

Thermal transport in organic/inorganic composites

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Frontiers in Energy 2018年第1期12卷 72-86页

作者： Bin LIU Lan DONG Qing Xi Xiangfan XU Jun ZHOU Baowen LI Center for Phononics and Thermal Energy Science China-EU JointCenter for Nanophononics Shanghai Key Laboratory of specialArtificial Microstructure Materials and Technology School of PhysicsScience and Engineering Tongji University Shanghai 200092 China Department of Mechanical Engineering University of ColoradoBoulder CO 80309 USA

Composite materials, which consist of organic and inorganic components, are widely used in various fields because of their excellent mechanical properties, resistance to corrosion, low-cost fabrication, etc. Thermal properties of organic/inorganic composites play a crucial role in some applications such as thermal interface materials for micro-electronic packaging, nano-porous materials for sensor development, thermal insulators for aerospace, and high-performance thermoelectric materials for power generation and refrigeration. In the past few years, many studies have been conducted to reveal the physical mechanism of thermal transport in organic/ inorganic composite materials in order to stimulate their practical applications. In this paper, the theoretical and experimental progresses in this field are reviewed. Besides, main factors affecting the thermal conductivity of organic/ inorganic compositcs are discussed, including the intrinsic properties of organic matrix and inorganic fillers, topolo- gical structure of composites, loading volume fraction, and the interfacial thermal resistance between fillers and organic matrix.

关键词： thermal conductivity organic/inorganic com-posites effective medium theory thermal percolationtheory interfacial thermal resistance

Towards two-dimensional room temperature multiferroics

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National Science Review 2020年第12期7卷 1844-1845页

作者： Hongjun Xiang Collaborative Innovation Center of Advanced Microstructures Key Laboratory of Computational Physical Sciences(Ministry of Education) State Key Laboratory of Surface Physicsand Department of PhysicsFudan University Shanghai Qi Zhi Institute

Multiferroic materials with coupled ferroelectricity (FE) and magnetism have long been sought for novel memory devices [1–3].The co-existence of FE and magnetism is rare in nature,which can be attributed to their mutual exclusive origins (empty d shell for conventional ferroelectric order and partially filled d shell for magnetic order).Moreover,

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Native point defects and oxygen migration of rare earth zirconate and stannate pyrochlores

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Journal of Materials Science & Technology 2021年第14期73卷 23-30页

作者： Juanli Zhao Yuchen Liu Yun Fan Wei Zhang Chengguan Zhang Guang Yang Hongfei Chen Bin Liu School of Materials Science and Engineering Shanghai UniversityShanghai200444China

Various excellent properties of rare earth zirconate and stannate pyrochlores are close related with their native point ***-principles calculations are performed to systematically investigate the point defect mechanism and the oxygen diffusion behavior of A_(2)B_(2)O_(7)(A=La,Ce,Pr,Nd,Pm,Sm,Eu,Gd;B=Zr,Sn).The possible defect complexes and their associated reactions under stoichiometric and nonstoichiometric conditions are *** O Frenkel pairs are the most stable defect structure in stoichiometric zirconates,whereas the cation antisite defects are the predominant one in stoichiometric *** the case of BO_(2) excess zirconates and stannates,the BA cation antisite defect with the A vacancy and/or the oxygen interstitial is energetically favorable,whereas the ABantisite defect together with the oxygen vacancy and/or the A interstitial is preferable under the A_(2)O_(3) excess ***,the maximum point defect concentrations of zirconates are much higher than those of ***,the oxygen migration barriers are similar in these compounds,ranging in 0.68 eV–0.80 *** predicted point defects and oxygen diffusion mechanisms play the critical role in their engineering applications and are expected to guide the future property improvement of pyrochlores through the control of point defects and/or composition.

关键词： Density-functional theory Pyrochlore Defect Migration Formation energies

Advances on strategies for searching for next generation thermal barrier coating materials

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Journal of Materials Science & Technology 2019年第5期35卷 833-851页

作者： Bin Liu Yuchen Liu Changhua Zhu Huimin Xiang Hongfei Chen Luchao Sun Yanfeng Gao Yanchun Zhou School of Materials Science and Engineering Shanghai University Shanghai 200444 China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Material & Processing Technology Beijing 100076 China High-performance Ceramics Division Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Thermal barrier coating(TBC) materials play important roles in gas turbine engines to protect the Nibased super-alloys from the high temperature airflow damage. High melting point, ultra-low thermal conductivity, large thermal expansion coefficient, excellent damage tolerance and moderate mechanical properties are the main requirements of promising TBC materials. In order to improve the efficiency of jet and/or gas turbine engines, which is the key of improved thrust-to-weight ratios and the energysaving, significant efforts have been made on searching for enhanced TBC materials. Theoretically, density functional theory has been successfully used in scanning the structure and properties of materials, and at the same time predicting the mechanical and thermal properties of promising TBC materials for high and ultrahigh temperature applications, which are validated by subsequent experiments. Experimentally,doping and/or alloying are also widely applied to further decrease their thermal conductivities. Now, the strategy through combining theoretical calculations and experiments on searching for next generation thermal insulator materials is widely adopted. In this review, the common used techniques and the recent advantages on searching for promising TBC materials in both theory and experiments are summarized.

关键词： Thermal barrier coatings Oxide First principles calculation Thermal properties Mechanical properties

Interpolation Technique for the Underwater DEM Generated by an Unmanned Surface Vessel

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Computer Modeling in Engineering & Sciences 2023年第9期136卷 3157-3172页

作者： Shiwei Qin Zili Dai Department of Civil Engineering Shanghai UniversityShanghai200444China

High-resolution underwater digital elevation models(DEMs)are important for water and soil conservation,hydrological analysis,and river channel *** this work,the underwater topography of the Panjing River in Shanghai,China,was measured by an unmanned surface *** different interpolation methods were used to generate the underwater DEM and their precision and applicability for different underwater landforms were analyzed through *** results showed that there was a positive correlation between the interpolation error and the terrain surface *** five interpolation methods were all appropriate for the survey area,but their accuracy varied with different surface *** on the analysis results,an integrated approach was proposed to automatically select the appropriate interpolation method according to the different surface roughness in the surveying *** approach improved the overall interpolation *** suggested technique provides a reference for the selection of interpolationmethods for underwater DEMdata.

关键词： Underwater DEM interpolation technique unmanned surface vessel surface roughness